The first catalytic asymmetric Wittig reaction is presented. Hydrogen-bond donors catalyze the [2+2] cycloaddition reaction between stabilized phosphorus ylides and 4-substituted cyclohexanones, breaking their symmetry plane and furnishing axially chiral olefins with moderate stereoselectivities. asymmetric catalysis - chirality - olefination - Wittig reaction - ylides
Highly enantioenriched products have been prepared in good yields from racemic enal starting materials through a new deracemization strategy that employs an enantioconvergent amino‐catalyzed symmetry‐making–symmetry‐breaking cascade. The reaction design features the tandem domination of product development and catalyst control in two reaction steps (see scheme).
Spirocyclic ureas, compositions containing such compounds and methods of use
申请人:Parmee R. Emma
公开号:US20060116366A1
公开(公告)日:2006-06-01
The present invention relates to spirocyclic ureas, compositions containing such compounds and methods of treatment The compounds are glucagon receptor antagonists and thus are useful for treating, preventing or delaying the onset of type 2 diabetes mellitus.